Brigadier-General Masoud Jazayeri, deputy chief of the Iranian armed forces, told a reporter this week that Iran would ‘not allow the enemy to advance’ in Syria. He said that no need had yet arisen for direct Iranian intervention in Syria, and expressed doubt that such a need would emerge. Another senior Iranian commander, General Hamid Reza Moqadam-Far of the Revolutionary Guards, echoed Jazayeri’s words. Moqadam-Far confirmed once more the presence of Iranian fighters in Syria, operating alongside the Assad regime’s forces.

The fighting words of these two senior Iranian military officials indicate just how determined Teheran is to stave off the loss of its key client in Damascus. But as is often the case with such public expressions, the ringing Iranian words of warning do not reflect Iranian strength. Rather, they are an indicator of the diminished and problematic situation facing the Iranians across the Middle East as a result of the re-shaping of the Arab world under way since last year.

With few assets remaining and little prospect of new gains, the Iranians are grimly determined to hold what they have. But their staunch backing of existing assets in Syria and Lebanon is itself serving to diminish their chances of spreading their influence further.

Iran’s bid for regional hegemony rests on its ability to successfully interfere in political processes across the Middle East. Central to this ability was the appeal of the Iranian revolutionary model, presented as an authentic, Muslim form of government, challenging the west and its puppets and clients. This all looks rather threadbare in the wake of the Arab upheavals.

As Sunni Islamism takes hold on the basis of mass popular support in key regional countries, the Iranians are discovering that their model of repressive Shia Islamic rule possesses little appeal. This has been demonstrated in a number of notable recent setbacks suffered by the Iranians. Additional mishaps have also reduced the Iranians’ reputation as savvy and feared covert operators.

In Tunisia this week, Sheikh Rachid Ghannouchi, the influential leader of the ruling an-Nahda party, issued a public apology to the people of Syria for having invited members of the Lebanese Hezbollah to Nahda’s 9th party convention. Ghannouchi stressed his party’s support for the Syrian revolution.

Hezbollah, once Iran’s main avenue to the hearts and minds of the Arabs, has become something of a toxic brand, because of movement leader Hassan Nasrallah’s unwavering and loudly expressed support for the Assad regime in Syria.

In Yemen, Iran has sought to build influence through clandestine backing of the Shia Houthi rebels in the country’s north. The Yemeni defense ministry last week announced that the authorities had successfully located and dismantled an Iranian spy network operating in the country. The network, Yemeni authorities alleged, was led by a former Revolutionary Guards commander.

The authorities in Sanaa see the apprehending of this network as important tangible proof confirming Iranian internal subversion in their country. The Iranians rapidly moved to try to prevent diplomatic damage. The foreign ministry in Teheran flatly denied the existence of the espionage cell. To no avail. This week Yemeni President Abd-Rabbu Mansour snubbed an Iranian envoy visiting the country who sought a meeting with him. The Gulf Cooperation Council, meanwhile, expressed its support for Yemen and its condemnation of Iran’s activities.

In all-important Egypt, too, the indications are that Iran is losing out to the Sunni Arabs in forging an alliance with the ascendant Muslim Brotherhood. In May, the Egyptian authorities foiled an Iranian plot to kidnap the Saudi ambassador to Cairo, Ahmed Qatan. President-elect Morsy’s office is in the process of taking legal action against the Iranian Fars news agency, for running an apparently bogus interview with him in June.

To this list can of course be added the now familiar stories of Hamas’s exit from the Iran-led regional alliance in recent months, and Iran’s failure, so far at least, to foment Shia versions of the Arab Spring in Bahrain, Kuwait and the eastern province of Saudi Arabia.

The slow crystallization of a Sunni Islamist bloc leaves Iran exposed as a sectarian, foreign, Shia force. The rhetoric of resistance is entirely inadequate to counter this – particularly since the main current evidence of Iranian power on the ground is in Teheran’s backing for Assad’s slaughter of mainly Sunni civilians in Syria.

Where there is a loser, of course, there is also a winner. In Syria, Egypt and Yemen, it is above all Saudi Arabia which is throwing money at the problems and as of now reaping the benefits of Sunni Islamism’s victories.

Saudi Arabia is an authoritarian, western-aligned regime. A key unanswered question remains whether Saudi petrodollars will keep the emerging Sunni Islamist governments focused on the Shia threat, or whether they will also find time and inclination to act against the west and Israel.

Nor do Saudi advances represent a victory for better governance in the region. A columnist in the Saudi-sponsored Sharq al-Awsat newspaper last week said that Iran’s ‘sectarian, racist and discriminatory’ regional policy has failed. It is worth noting that the Saudis themselves and their allies are no less notable for these three aspects than are the Iranians and their allies.

But what can be said with confidence is that Iran and its Shia-led bloc have emerged as among the main victims of the Arab ferment of 2011-12. Teheran wanted to be engaged by now in a battle with a retreating west for the leadership of the Muslim Middle East. Instead, it finds itself embroiled in a sectarian rearguard action, desperately and brutally trying to preserve its assets against the advance of a rising Sunni alignment.